1. Field of the Invention
The present invention relates to a firmware distributing device, program, and method which download firmware to a plurality of terminal devices via a network, and particularly relates to a firmware distributing device, program, and method which appropriately process the download of firmware to a plurality of terminal devices which share a communication line.
2. Description of the Related Arts
Conventionally, the firmware distributing system which applies modified firmware by downloading the modified firmware to a plurality of terminal devices via a network is, for example, the one shown in FIG. 26. In FIG. 26, the firmware distributing system connects a plurality of terminal devices 202-1 to 202-n to a center device 200 via a communication line such as a network 204. The terminal devices 202-1 to 202-n store firmware 206-1 to 206-n and execute necessary terminal control processes by executing the firmware 206-1 to 206-n. When the firmware 206-1 to 206-n stored in the terminal devices 202-1 to 202-n is to be modified, modified firmware 208 is registered to the center device 200. Each of the terminal devices 202-1 to 202-n transmits a download request to the center device 200 at a scheduled constant time interval or at the timing ordered by the operation of an operator and checks whether the modified firmware 208 is registered in the center device 200. When the modified firmware 208 is registered in the center device 200, the modified firmware 208 is downloaded to carry out update, thereby applying it to the device. However, in such a conventional firmware distributing system, in the case in which each of the plurality of terminal devices checks at every constant cycle whether the firmware to be modified is registered in the center device and downloads the firmware, if the firmware is downloaded in the same time period by a plurality of the terminal devices, the download time becomes extremely long when they are the plurality of terminal devices sharing a communication line and belonging to, for example, the same customer site, the processes of the download may be terminated due to communication timeout, and, at the same time, the resource of the center side is occupied during that period, which has been problems. In order to solve these problems, conventionally, as shown in FIG. 27, with respect to the terminal devices 202-1 to 202-3 of the same customer site sharing the communication line, the download start time of the firmware is set in advance so as to be mutually shifted like time t1, t2, and t3, thereby providing a countermeasure so that the download time is not mutually overlapped.    Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2005-242447
However, in such a conventional method of setting the download start time of the firmware in advance so that the time is mutually shifted among the plurality of terminal devices sharing the communication line, for example, as shown in FIG. 28, when the degree of shifting of the time is not enough among the plurality of devices 202-1 to 202-3 sharing the communication line, the download time is mutually overlapped, which is a problem. Moreover, even when the degree of shifting of the download start time of the plurality of devices 202-1 to 202-3 sharing the communication line is appropriate in the beginning as shown in FIG. 27, when the firmware to be modified becomes large and the download time becomes long as shown in FIG. 29, the download time is mutually overlapped, which is a problem. Moreover, with respect to the download request of the firmware ordered by the operator, the firmware is immediately downloaded when the modified firmware has been registered. However, if another terminal device sharing the communication line is downloading firmware at this point, the download time takes longer by the amount corresponding to sharing of the communication line, and the operator is excessively kept waiting by that amount, which is a problem.